如何计算 pandas dataframe 中列值更改的频率？

Question

I have a pandas data frame that looks like:

Index  Activity
0          0
1          0
2          1
3          1
4          1
5          0
...
1167       1
1168       0
1169       0

I want to count how many times it changes from 0 to 1 and when it changes from 1 to 0, but I do not want to count how many 1's or 0's there are. For example, if I only wanted to count index 0 to 5, the count for 0 to 1 would be one.

How would I go about this? I have tried using some_value

Answer 1

This is a simple approach that can also tell you the index value when the change happens. Just add the index to a list.

c_1to0 = 0
c_0to1 = 0
for i in range(0, df.shape[0]-1):
    if df.iloc[i]['Activity'] == 0 and df.iloc[i+1]['Activity'] == 1:
        c_0to1 +=1
    elif df.iloc[i]['Activity'] == 1 and df.iloc[i+1]['Activity'] == 0:
        c_1to0 +=1